Within the IP (Internet Protocol) Multimedia Subsystem (IMS) as defined by 3rd Generation Partnership Project (3GPP) Session Initiation Protocol (SIP) defined by Internet Engineering Task Force (IETF) is used for controlling communication. SIP is an application-layer control protocol for creating, modifying, and terminating sessions with one or more participants. These sessions may include Internet multimedia conferences, Internet telephone calls, and multimedia distribution. Members in a session can communicate via multicast or via a mesh of unicast relations, or a combination of these. Session Description Protocol (SDP) is a protocol which conveys information about media streams in multimedia sessions to allow the recipients of a session description to participate in the session. The SDP offers and answers can be carried in SIP messages. Diameter protocol has been defined by IETF and is intended to provide an Authentication, Authorization and Accounting (AAA) framework for applications such as network access or IP mobility.
Generally, for properly establishing and handling a communication connection between network elements such as a user equipment and another communication equipment or user equipment, a database, a server, etc., one or more intermediate network elements such as control network elements, support nodes, service nodes and interworking elements are involved which may belong to different communication networks.
The IMS can support wildcarded public user identities (IMPU). The wildcarded IMPU concept has been introduced to cover a range/group of IMPUs to simplify administration efforts, with the pre-condition that all IMPUs within a wildcarded IMPU are assigned to the same service profile. Furthermore, distinct IMPU was defined as public user identity to identity an IMS user.
An example of a wildcarded IMPU, all Tel-URIs can begin with +123 for a company behind an IP private branch exchange (IP-PBX). Extended Regular Expression (ERE) can be used to define a wildcarded IMPU. Such a wildcarded IMPU can have the format of “tel:+123!.*!”
As seen, wildcarded public user identities can enable optimisation of the operation and maintenance of the nodes for the case in which a large amount of users are registered together and handled in the same way by the network. However, there are cases that some of the IMPUs covered by a wildcarded IMPU shall have different service profiles, for example, directors of the company. However, as mentioned above all IMPUs covered by a wildcarded IMPU can only have the same service profile.